I'm the maintainer for subclipse, gef, emf, phpeclipse and mylyn. They work fine for me. First of all, do you see them in Help -> About Eclipse SDK -> Plug-in Details? And do you see Mylyn in Feature Details?

Could some dev assign this bug to me? I'm just a TU.

no

I attached configuration details

my feature details:
CVS
Java devlopment tools
Eclipse platform
Eclipse Project SDK
Eclipse RCP
Help system base
PDE

Ok, I'll start with the questions.

Is your system fully updated?
What java-runtime provider are you using? Have you tried the other ones? (openjdk6 is the one we officially support in [extra])
Which architecture do you run?
Does starting with a clean ~/.eclipse and workspace help?
Did any plugin work before?

Ok, so:

fully updated system
Started off with jdk/jre (sun), tried openjdk, then switched back to jre/jdk (pacman -Rnu)
Just installed eclipse + plugins for the first time in one shot a few days ago, after switching back to jre/jdk (without a ~/.eclipse)
installation went smoothly, no scriptlet errors etc
so i never had any plugins work
2.6.28-ARCH #1 SMP PREEMPT (i686)
I tried rm -r ~/.eclipse, reinstalling eclipse-mylyn, then reinstalling and restarting eclipse: without luck

attached a file-listing of /usr/share/eclipse

Could you please try with openjdk6 just to rule out the JVM problem?

I also experience the absence of CDT although it should be installed... Could you state once more what should I check? What should I do about that openjdk6?

Similar issue on Arch x86_64 with openjdk and jre/jdk. But some plugins working for me after running 'eclipse -clean' (CDT and cmakeed). Also all ok if just download tarball with eclipse extract and install plugins (any) manually.

@Matěj: sorry for the late answer. Just check you have openjdk6 installed, and if you don't, try to install it and see if something changes. I don't think it will work, given Artyom's comment, but it's worth a try...

I had the same, try uninstall plugins one by one, starting from pydev and phpeclipse.

I have the same issue on an up to date system.
Removed all eclipse packages and re-installed all except pydev
Seems to working fine - but on my system, pydev seems to be a problem

local/eclipse 3.4.1-1
An IDE for Java and other languages
local/eclipse-cdt 5.0.2-1
C/C++ Plugin for Eclipse
local/eclipse-ecj 3.3.2-2
Eclipse java bytecode compiler
local/eclipse-epic 0.6.13-2
Perl development framework for the Eclipse platform
local/eclipse-pydev 1.4.4-1
Plugin for using Eclipse as a Python IDE
local/eclipse-subclipse 1.4.6-1
Subversion integration for the Eclipse platform

I have now installed PyDev using the Update Manager in Eclipse, and everything is fine.

I have now installed PyDev using the Update Manager in Eclipse, and everything is fine.

Here is corrected PKGBUILD to eclipse-pydev:)

I had to downgrade eclipse-pydev-1.4.4-1.pkg.tar.gz to eclipse-pydev-1.3.24-1.pkg.tar.gz and eclipse-cdt-5.0.2-1-i686.pkg.tar.gz to eclipse-cdt-5.0.1-1-i686.pkg.tar.gz.
Now its working.

but I corrected eclipse-pydev package:P PKGBUILD is in my comment above:)

Well... I don't know how to use your PKGBUILD, but the current repository version is still not working... =(

I had the same issue. PKGBUILD from Lukasz did the job. The plugin works but the features are copied to wrong directory - "...dropins/pydev/eclipse/feature/" instead of "...dropins/pydev/features/". While this doesn't affect plugin functionality plugin logo is not shown on about box as well as in the features list.
Same issue with upgrade to 1.4.5 from the repository.

this is still valid ?

I think you can close it:)